Anticoagulants are used to treat and prevent blood clots that may occur in your blood vessels. Blood clots can block blood vessels (an artery or a vein). A blocked artery stops blood and oxygen from getting to a part of your body (for example, to a part of the heart, brain or lungs).

1. Anticoagulants and
Fibrinolytics
Prof. Amol B. Deore
Department of Pharmacology
MVPs Institute of Pharmaceutical Sciences, Nashik

2. Blood Clotting (or coagulation)
•Blood clotting is a complex process of the
formation of semisolid insoluble gel of blood &
fibrin threads at the damaged wall of blood vessel.
•Blood clotting involves several enzymes and other
chemicals known as clotting factors

3. Clotting factors

6. Anticoagulants
Anticoagulants are a class of
drugs that prevent the
coagulation (clotting) of blood.
Anticoagulants reduce blood
clotting which can help in
management of deep vein
thrombosis, pulmonary
embolism, myocardial
infarction and ischemic stroke.

7. Anticoagulants
CLASSIFICATION
A. Heparin and derivative substances:
Ex. Enoxaparin, Nadroparin, Reviparin,
Parnaparin, Certoparin, Dalteparin, Tinzaparin
B. Direct thrombin inhibitors:
Ex. Hirudin, Lepirudin, Bivalirudin, Argatroban, Dabigatran
C. Coumarin derivatives:
Ex. Warfarin (Coumadin), Acenocoumarol, Phenprocoumon, Bishydroxycoumarin
D. Indanediones derivatives:
Ex. Phenindione, Diphenindione, Anisindione
E. Fibrinolytic drugs:
Ex. Streptokinase, Urokinase, alteplase, Anistrelase

8. Clot formation
• Blood coagulation is the conversion of liquid blood into a solid
gel, known as a clot.
A clot:
• Consists of a meshwork of fibrin within which blood cells are
trapped
• Functions to reinforce the platelet plug.

9. Thrombosis
• Thrombosis is the pathological formation of a
clot known as a thrombus, which may cause
occlusion within blood vessels or the heart,
and result in death.
Thrombosis causes:
• Arterial occlusion – which may lead to
myocardial infarction, stroke and peripheral
ischaemia.
• Venous occlusion – which may lead to deep
venous thrombosis and pulmonary embolism.

11. Heparin
•Heparin, prepared commercially from animal tissue,
is an antithrombolytic agent used to treat and
prevent clot formation.
•Because it doesn’t affect the synthesis of clotting
factors, heparin can’t dissolve already-formed clots.

12. Types of heparin
•Unfractionated heparin (UFH)
•Low-molecular-weight heparin (LMWH):
Enoxaparin, Nadroparin, Reviparin, Parnaparin,
Certoparin, Dalteparin, Tinzaparin
•LMWH Used to prevent deep vein thrombosis (DVT) (a
blood clot in the deep veins, usually of the legs) in
surgical patients.

14. Mode of action of heparin
• Heparin prevents the formation of new thrombus
• Heparin inhibits the formation of thrombin and fibrin by
activating antithrombin III.
• Antithrombin III then inactivates factors IXa, Xa, XIa, and XIIa
in the intrinsic and common pathways. The end result is
prevention of a stable fibrin clot.
• In low doses, heparin increases the activity of antithrombin III
against factor Xa and thrombin and inhibits clot formation.

15. • Heparin inhibits the conversion of prothrombin into thrombin and has
an anti-thromboplastin effect.
• Prothrombin thromboplastin X thrombin

16. Clinical uses of Heparin
• Heparin may be used in a number of clinical situations to prevent the
formation of new clots or the extension of existing clots.
• It is use as an anticoagulant in vascular surgery and occasionally in blood
transfusion.
• It is mainly used in the treatment of arterial and venous thrombosis.
• Deep venous thrombosis
• Myocardial infarction
• Prevention of postoperative thrombosis
• Prevention of peripheral arterial embolism
• Disseminated intravascular coagulation

17. To be continued…
• treating arterial clotting and preventing embolus
formation in patients with atrial fibrillation, an arrhythmia
in which ineffective atrial contractions cause blood to pool
in the atria, increasing the risk of clot formation
• preventing thrombus formation and promoting cardiac
circulation in an acute myocardial infarction (MI) by
preventing further clot formation at the site of the already
formed clot.

18. Heparin can be used to prevent clotting
whenever the patient’s blood must circulate
outside the body through a machine, such as
the cardiopulmonary bypass machine or
hemodialysis machine, and during blood
transfusions.

19. ORAL ANTICOAGULANT
•Ex.:- Warfarin, Bishydroxy coumarin, Ethyl
biscoumacetate, Phenoprocuman, Cyclocoumarol.

20. Mode of action of oral anticoagulants
• Oral anticoagulants alter the ability of the liver to
synthesize vitamin K–dependent clotting factors,
including prothrombin and factors VII, IX, and X.
• However, clotting factors already in the bloodstream
continue to coagulate blood until they become
depleted, so anticoagulation doesn’t begin immediately.

21. To be continued
• The coumarins and indanediones act by reducing the
synthesis of prothrombin like clotting factor VII, factor IX,
and factor X by liver.
• The normal synthesis of these four factors requires vitamin
k. Thus oral anticoagulants inhibit the activity of vitamin k.
• They also show antithrombin activity
• The anticoagulant effect an average takes 36-48 hours to
build up.

22. Therapeutic uses:-
• Venous thromboembolism
• Arterial thrombosis
• Deep venous thrombosis and pulmonary embolism.
• Acute myocardial infarction
• Acute coronary insufficiency and angina pectoris
• Cerebrovascular disease
• Retinal vein or artery thrombosis
• Vascular surgery.

23. Fibrinolytic drugs:
• Fibrinolytic drugs have ability to effectively dissolve
blood clots.
• They are used in acute pulmonary emboli,
intracoronary emboli and management of myocardial
infarction
• Ex. Streptokinase, Urokinase, alteplase, Anistrelase.